The US government doesn't restrict freedom of speech to such a degree that it allows for non-government actors (including political parties, partisans and those monetarily interested in obfuscation) to decrease the signal to noise ratio of truth (signal) to misinformation and the like (noise).

That is a lot different than the government itself getting into the misinformation business itself.

That can be summed up that don't have regulations on limiting speech when it isn't truthful, except when it incites violence and other limited times like libel, and even then the legal bar is very high to have the legal basis to successfully bring a case.

There is no restriction on reporting the truth. Classified information gets leaked in the press on a fairly frequent basis without any ramifications to the journalists publishing it. It seems fairly often those who leak it aren't charged. Those cases where they are charged are when they don't just verbally say to a reporter off the record, but when they leak documents.